Simultaneous voltammetric determination of ascorbic acid, dopamine, acetaminophen and tryptophan based on hybrid trimetallic nanoparticles-capped electropretreated graphene

•A novel nanocomposite based on the (Au/Ag/Pd)NPs/EPGr was fabricated.•The nanocomposite was applied for the simultaneous determination for AA, DA, AP and TP.•A high sensitive and large separation peak potentials for AA–DA, DA–AP, and AP–TP were observed.•The low limits of detection for AA, DA, AP and TP were estimated as compared to other reports.•The nanocomposite successfully applied for the determination of these species in real sample.